They even use their own flesh and blood to get at you, they punish them as you arnt speaking him they have no concience on what they do, if he loved your Son what you do or dont do would not be affected , the children are pawns for them to use as weapons.
Maybe your Son is trying to get him tobe a Dad by going to the pub, he needs a Dad but cant see that his Dad is not being a Dad.
Mine knocked my Sons confidence so much many years ago an he lost a job through it, he used to swear at him and call him names yet now its more me that my Son avoids and his Dad is treated better.
No way of understanding the effects of abuse have on our children, he may feel controlled or trying to cover up what hid dad has done to him by trying to be friends with him so he does not have to face the pain of what he has done to him , to kind of win his dads approvalx